The present inventive concept relates to a method for detecting impurities in ammonium hydroxide.
Various kinds of chemicals are used in manufacturing processes for highly integrated semiconductor devices. For example, ammonium hydroxide (NH4OH) is utilized to remove polysilicon in the manufacturing process for semiconductor devices. The semiconductor devices may suffer from impurities contained in the ammonium hydroxide. For example, in the manufacturing process for semiconductor devices, a silicon gate may be formed to serve as a dummy gate. The ammonium hydroxide may remove the silicon gate to form a metal gate. However, impurities contained in the ammonium hydroxide may cause damage to not only the polysilicon but also to the metal and its nitride, such as TiN, thus reducing the reliability of the semiconductor device.